Van der Linde, M. et al (2019): An assessment of sperm whale occurrence and social structure off São Miguel Island

Van der Linde and Eriksson (2019) assessed sperm whale (Physeter macrocephalus) occurrence and social structure around São Miguel, Azores, using fluke and dorsal identification photographs from 2010 to 2017.

Objectives

To assess the year-round occurrence of sperm whales (Physeter macrocephalus) off São Miguel Island, Azores, using photo-identification techniques (flukes and dorsal fins).
To investigate the social structure of sperm whales, including the identification of social units and analyzing associations between individuals.
To explore the use of dorsal photos as a supplementary method for identifying individuals and re-identifying whales with less distinct fluke marks.

Impact

The study identified 12 social units of sperm whales, with unit sizes ranging from 2 to 13 individuals, and observed long-term site fidelity within units.
Females and immature whales were encountered more frequently than mature males, with resightings mostly occurring within the same year.
The dorsal photo-identification technique proved useful for identifying individuals, particularly when fluke marks were not visible or had changed over time.
The social structure of sperm whales around São Miguel shows both stable and dynamic associations within and between units, with some evidence for preferred associations between specific units.
The research calls for continued photo-ID efforts to enhance the understanding of sperm whale social organization and to investigate the factors that influence their social dynamics.

Supported UN Global Goals

Studying sperm whale social structure and occurrence off São Miguel, Azores, van der Linde and Eriksson (2019) provide to Sustainable Development Goal 14 (Life Below Water). Photo identification is used to monitor site fidelity, social units and associations, yielding important data on the conservation and management of this species in the Azores and to help develop sustainable whale watching practices.